Clark P A, Iranmanesh A, Veldhuis J D, Rogol A D
Department of Pediatrics, University of Virginia, Charlottesville 22908, USA.
J Clin Endocrinol Metab. 1997 Sep;82(9):2950-5. doi: 10.1210/jcem.82.9.4262.
The assessment of pulsatile GnRH activity in children has become possible since the introduction of the sensitive third generation immunochemiluminescent assays, permitting detection of previously unmeasurable levels of LH and FSH. Despite this, however, studies differ with regard to pulse frequency and the presence of a diurnal variation in LH secretion in clinically prepubertal children. Discrepancies may reflect the limitations of relatively long intersampling intervals, less sensitive LH assays such as RIAs, and the use of algorithms to analyze pulsatile LH secretion, which do not account for endogenous production rates and metabolic clearance. To address this, we studied LH secretion in 10 prepubertal children (4 boys and 6 girls, age 8.5-10.8 y) and 12 young adults (7 men and 5 women in the early follicular phase, age 18.6-32.8 y). Blood was sampled every 5 min from 2000 h to 0200 h (nighttime) and from 0800 h to 1400 h (daytime) for LH determination, using an immunochemiluminescent assay. Deconvolution analysis revealed no difference between daytime and nighttime LH secretion, including LH secretory amplitude and pulse frequency, within any of the 4 groups, permitting pooling of the data from the 2 sampling intervals for analysis. In addition, there was no difference in LH secretion or half-life between genders. Comparison of pulsatile LH secretion between children and adults revealed a marked increase in the mass and amplitude of LH secreted per burst. LH secretory burst mass rose 9.5-fold in females, increasing the mean LH concentration by nearly 13-fold and the production rate by nearly 9-fold. The trend in males was similar although less remarkable, with a 4.2-fold rise in LH secretory burst mass from childhood to adulthood. No differences in pulse frequency, interburst interval, half-life, or approximate entropy were found between prepubertal children and adults. We conclude that the maturational change in LH secretion occurs via a highly specific mass/amplitude-dependent mechanism without significant gender or day/night differences.
自从引入灵敏的第三代免疫化学发光测定法以来，对儿童搏动性促性腺激素释放激素（GnRH）活性的评估已成为可能，这使得检测以前无法测量的促黄体生成素（LH）和促卵泡生成素（FSH）水平成为可能。然而，尽管如此，关于临床青春期前儿童的LH脉冲频率和LH分泌的昼夜变化情况，各项研究结果并不一致。差异可能反映出相对较长的采样间隔时间的局限性、诸如放射免疫分析（RIA）等不太灵敏的LH测定方法，以及使用算法来分析搏动性LH分泌，而这些算法没有考虑内源性生成率和代谢清除率。为了解决这个问题，我们研究了10名青春期前儿童（4名男孩和6名女孩，年龄8.5 - 10.8岁）和12名年轻成年人（7名男性和5名处于卵泡早期的女性，年龄18.6 - 32.8岁）的LH分泌情况。从20:00至02:00（夜间）以及从08:00至14:00（白天），每隔5分钟采集一次血液样本用于LH测定，采用免疫化学发光测定法。去卷积分析显示，在4组中的任何一组内，白天和夜间的LH分泌情况没有差异，包括LH分泌幅度和脉冲频率，这使得可以将来自两个采样间隔的数据合并进行分析。此外，不同性别之间的LH分泌或半衰期没有差异。儿童与成年人之间搏动性LH分泌的比较显示，每次脉冲分泌的LH量和幅度显著增加。女性的LH分泌脉冲量增加了9.5倍，平均LH浓度增加了近13倍，生成率增加了近9倍。男性的趋势相似，尽管不太明显，从儿童期到成年期LH分泌脉冲量增加了4.2倍。青春期前儿童与成年人之间在脉冲频率、脉冲间隔、半衰期或近似熵方面没有发现差异。我们得出结论，LH分泌的成熟变化是通过一种高度特异性的、依赖量/幅度的机制发生的，不存在明显的性别或昼夜差异。
